If your sister in law is your wife's sister then she would be nothing to your sister.
However if your sister in law is your brother's wife then she would also be your sister's sister in law.
a cow
if my sister had a baby boy what would he be to me
Yes, I suppose that they would be sister-in-laws. Because your sister is your husband's sister-in-law, and the other sister is his sibling, then I suppose they would be sister-in-laws.
If it was "please don't bother my sister and ___."It would be me, but if it was "My sister and ___ are going to the movies," it would be I.
Your mother's sister would be your aunt. Your father's sister would also be your aunt.
your mother's sister would be your aunt
Your mother's sister's husband's sister is your aunt's sister-in-law, but is not related to you. Here's why: Your mother's sister is your aunt. The sister of a woman's husband would be her sister-in-law. In this case the woman is your aunt. So your mother's sister's husband's sister would be your aunt's sister-in-law.
The sister of your husband is your sister-in-law.
She would be your step-sister
Your sister in law is your husband's sister or your brother's wife.
Your Sister-in-law
Sister is a singular term, not plural, therefore you would say how is your sister, not how are your sister.